SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1bcb2f3d1b41cb30ba9c6e037454aab1f563208d66be2cca7c2bc0dda3a903e' 
  AND token = 'upjCe9newST6YMkjA/ry8NfYwEfWyhsmj/t53rovYqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}